Move desugarings to lowering step

mk/crates.mk

@@ -61,51 +61,55 @@ HOST_CRATES := syntax $(RUSTC_CRATES) rustdoc fmt_macros
 TOOLS := compiletest rustdoc rustc rustbook error-index-generator
 
 DEPS_core :=
+DEPS_alloc := core libc alloc_system
+DEPS_alloc_system := core libc
+DEPS_collections := core alloc rustc_unicode
 DEPS_libc := core
+DEPS_rand := core
+DEPS_rustc_bitflags := core
 DEPS_rustc_unicode := core
-DEPS_alloc := core libc alloc_system
+
 DEPS_std := core libc rand alloc collections rustc_unicode \
 	native:rust_builtin native:backtrace \
 	alloc_system
+DEPS_arena := std
+DEPS_glob := std
+DEPS_flate := std native:miniz
+DEPS_fmt_macros = std
+DEPS_getopts := std
 DEPS_graphviz := std
+DEPS_log := std
+DEPS_num := std
+DEPS_rbml := std log serialize
+DEPS_serialize := std log
+DEPS_term := std log
+DEPS_test := std getopts serialize rbml term native:rust_test_helpers
+
 DEPS_syntax := std term serialize log fmt_macros arena libc rustc_bitflags
+
+DEPS_rustc := syntax flate arena serialize getopts rbml rustc_front\
+              log graphviz rustc_llvm rustc_back rustc_data_structures
+DEPS_rustc_back := std syntax rustc_llvm rustc_front flate log libc
+DEPS_rustc_borrowck := rustc rustc_front log graphviz syntax
+DEPS_rustc_data_structures := std log serialize
 DEPS_rustc_driver := arena flate getopts graphviz libc rustc rustc_back rustc_borrowck \
                      rustc_typeck rustc_mir rustc_resolve log syntax serialize rustc_llvm \
 		             rustc_trans rustc_privacy rustc_lint rustc_front
 
-DEPS_rustc_trans := arena flate getopts graphviz libc rustc rustc_back \
-	                log syntax serialize rustc_llvm rustc_front rustc_platform_intrinsics
-DEPS_rustc_mir := rustc rustc_front syntax
-DEPS_rustc_typeck := rustc syntax rustc_front rustc_platform_intrinsics
-DEPS_rustc_borrowck := rustc rustc_front log graphviz syntax
-DEPS_rustc_resolve := rustc rustc_front log syntax
-DEPS_rustc_privacy := rustc rustc_front log syntax
+DEPS_rustc_front := std syntax log serialize
 DEPS_rustc_lint := rustc log syntax
-DEPS_rustc := syntax flate arena serialize getopts rbml \
-              log graphviz rustc_llvm rustc_back rustc_data_structures
 DEPS_rustc_llvm := native:rustllvm libc std rustc_bitflags
+DEPS_rustc_mir := rustc rustc_front syntax
+DEPS_rustc_resolve := rustc rustc_front log syntax
 DEPS_rustc_platform_intrinsics := rustc rustc_llvm
-DEPS_rustc_back := std syntax rustc_llvm rustc_front flate log libc
-DEPS_rustc_front := std syntax log serialize
-DEPS_rustc_data_structures := std log serialize
+DEPS_rustc_privacy := rustc rustc_front log syntax
+DEPS_rustc_trans := arena flate getopts graphviz libc rustc rustc_back \
+                    log syntax serialize rustc_llvm rustc_front rustc_platform_intrinsics
+DEPS_rustc_typeck := rustc syntax rustc_front rustc_platform_intrinsics
+
 DEPS_rustdoc := rustc rustc_driver native:hoedown serialize getopts \
                 test rustc_lint rustc_front
-DEPS_rustc_bitflags := core
-DEPS_flate := std native:miniz
-DEPS_arena := std
-DEPS_graphviz := std
-DEPS_glob := std
-DEPS_serialize := std log
-DEPS_rbml := std log serialize
-DEPS_term := std log
-DEPS_getopts := std
-DEPS_collections := core alloc rustc_unicode
-DEPS_num := std
-DEPS_test := std getopts serialize rbml term native:rust_test_helpers
-DEPS_rand := core
-DEPS_log := std
-DEPS_fmt_macros = std
-DEPS_alloc_system := core libc
+
 
 TOOL_DEPS_compiletest := test getopts
 TOOL_DEPS_rustdoc := rustdoc

src/librustc/middle/astencode.rs

@@ -36,6 +36,7 @@ use middle::subst;
 use middle::ty::{self, Ty};
 
 use syntax::{ast, ast_util, codemap};
+use syntax::ast::NodeIdAssigner;
 use syntax::codemap::Span;
 use syntax::ptr::P;
 
@@ -53,8 +54,9 @@ use serialize::EncoderHelpers;
 
 #[cfg(test)] use std::io::Cursor;
 #[cfg(test)] use syntax::parse;
+#[cfg(test)] use syntax::ast::NodeId;
 #[cfg(test)] use rustc_front::print::pprust;
-#[cfg(test)] use rustc_front::lowering::lower_item;
+#[cfg(test)] use rustc_front::lowering::{lower_item, LoweringContext};
 
 struct DecodeContext<'a, 'b, 'tcx: 'a> {
     tcx: &'a ty::ctxt<'tcx>,
@@ -1373,6 +1375,22 @@ impl FakeExtCtxt for parse::ParseSess {
     fn parse_sess(&self) -> &parse::ParseSess { self }
 }
 
+#[cfg(test)]
+struct FakeNodeIdAssigner;
+
+#[cfg(test)]
+// It should go without saying that this may give unexpected results. Avoid
+// lowering anything which needs new nodes.
+impl NodeIdAssigner for FakeNodeIdAssigner {
+    fn next_node_id(&self) -> NodeId {
+        0
+    }
+
+    fn peek_node_id(&self) -> NodeId {
+        0
+    }
+}
+
 #[cfg(test)]
 fn mk_ctxt() -> parse::ParseSess {
     parse::ParseSess::new()
@@ -1391,23 +1409,29 @@ fn roundtrip(in_item: P<hir::Item>) {
 #[test]
 fn test_basic() {
     let cx = mk_ctxt();
-    roundtrip(lower_item(&quote_item!(&cx,
+    let fnia = FakeNodeIdAssigner;
+    let lcx = LoweringContext::new(&fnia, None);
+    roundtrip(lower_item(&lcx, &quote_item!(&cx,
         fn foo() {}
     ).unwrap()));
 }
 
 #[test]
 fn test_smalltalk() {
     let cx = mk_ctxt();
-    roundtrip(lower_item(&quote_item!(&cx,
+    let fnia = FakeNodeIdAssigner;
+    let lcx = LoweringContext::new(&fnia, None);
+    roundtrip(lower_item(&lcx, &quote_item!(&cx,
         fn foo() -> isize { 3 + 4 } // first smalltalk program ever executed.
     ).unwrap()));
 }
 
 #[test]
 fn test_more() {
     let cx = mk_ctxt();
-    roundtrip(lower_item(&quote_item!(&cx,
+    let fnia = FakeNodeIdAssigner;
+    let lcx = LoweringContext::new(&fnia, None);
+    roundtrip(lower_item(&lcx, &quote_item!(&cx,
         fn foo(x: usize, y: usize) -> usize {
             let z = x + y;
             return z;
@@ -1424,10 +1448,12 @@ fn test_simplification() {
             return alist {eq_fn: eq_int, data: Vec::new()};
         }
     ).unwrap();
-    let hir_item = lower_item(&item);
+    let fnia = FakeNodeIdAssigner;
+    let lcx = LoweringContext::new(&fnia, None);
+    let hir_item = lower_item(&lcx, &item);
     let item_in = InlinedItemRef::Item(&hir_item);
     let item_out = simplify_ast(item_in);
-    let item_exp = InlinedItem::Item(lower_item(&quote_item!(&cx,
+    let item_exp = InlinedItem::Item(lower_item(&lcx, &quote_item!(&cx,
         fn new_int_alist<B>() -> alist<isize, B> {
             return alist {eq_fn: eq_int, data: Vec::new()};
         }

src/librustc/middle/effect.rs

@@ -102,7 +102,6 @@ impl<'a, 'tcx, 'v> Visitor<'v> for EffectCheckVisitor<'a, 'tcx> {
     fn visit_block(&mut self, block: &hir::Block) {
         let old_unsafe_context = self.unsafe_context;
         match block.rules {
-            hir::DefaultBlock => {}
             hir::UnsafeBlock(source) => {
                 // By default only the outermost `unsafe` block is
                 // "used" and so nested unsafe blocks are pointless
@@ -131,6 +130,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for EffectCheckVisitor<'a, 'tcx> {
                 self.unsafe_context.push_unsafe_count =
                     self.unsafe_context.push_unsafe_count.checked_sub(1).unwrap();
             }
+            hir::DefaultBlock | hir::PushUnstableBlock | hir:: PopUnstableBlock => {}
         }
 
         visit::walk_block(self, block);

src/librustc/middle/region.rs

@@ -377,7 +377,7 @@ impl RegionMaps {
         self.code_extents.borrow()[e.0 as usize]
     }
     pub fn each_encl_scope<E>(&self, mut e:E) where E: FnMut(&CodeExtent, &CodeExtent) {
-        for child_id in (1..self.code_extents.borrow().len()) {
+        for child_id in 1..self.code_extents.borrow().len() {
             let child = CodeExtent(child_id as u32);
             if let Some(parent) = self.opt_encl_scope(child) {
                 e(&child, &parent)

src/librustc/middle/stability.rs

@@ -270,7 +270,8 @@ pub fn check_unstable_api_usage(tcx: &ty::ctxt)
     let mut checker = Checker {
         tcx: tcx,
         active_features: active_features,
-        used_features: FnvHashMap()
+        used_features: FnvHashMap(),
+        in_skip_block: 0,
     };
 
     let krate = tcx.map.krate();
@@ -283,14 +284,23 @@ pub fn check_unstable_api_usage(tcx: &ty::ctxt)
 struct Checker<'a, 'tcx: 'a> {
     tcx: &'a ty::ctxt<'tcx>,
     active_features: FnvHashSet<InternedString>,
-    used_features: FnvHashMap<InternedString, attr::StabilityLevel>
+    used_features: FnvHashMap<InternedString, attr::StabilityLevel>,
+    // Within a block where feature gate checking can be skipped.
+    in_skip_block: u32,
 }
 
 impl<'a, 'tcx> Checker<'a, 'tcx> {
     fn check(&mut self, id: DefId, span: Span, stab: &Option<&Stability>) {
         // Only the cross-crate scenario matters when checking unstable APIs
         let cross_crate = !id.is_local();
-        if !cross_crate { return }
+        if !cross_crate {
+            return
+        }
+
+        // We don't need to check for stability - presumably compiler generated code.
+        if self.in_skip_block > 0 {
+            return;
+        }
 
         match *stab {
             Some(&Stability { level: attr::Unstable, ref feature, ref reason, issue, .. }) => {
@@ -369,6 +379,21 @@ impl<'a, 'v, 'tcx> Visitor<'v> for Checker<'a, 'tcx> {
                   &mut |id, sp, stab| self.check(id, sp, stab));
         visit::walk_pat(self, pat)
     }
+
+    fn visit_block(&mut self, b: &hir::Block) {
+        let old_skip_count = self.in_skip_block;
+        match b.rules {
+            hir::BlockCheckMode::PushUnstableBlock => {
+                self.in_skip_block += 1;
+            }
+            hir::BlockCheckMode::PopUnstableBlock => {
+                self.in_skip_block = self.in_skip_block.checked_sub(1).unwrap();
+            }
+            _ => {}
+        }
+        visit::walk_block(self, b);
+        self.in_skip_block = old_skip_count;
+    }
 }
 
 /// Helper for discovering nodes to check for stability

src/librustc/middle/ty/context.rs

@@ -219,7 +219,7 @@ pub struct ctxt<'tcx> {
     /// Common types, pre-interned for your convenience.
     pub types: CommonTypes<'tcx>,
 
-    pub sess: Session,
+    pub sess: &'tcx Session,
     pub def_map: DefMap,
 
     pub named_region_map: resolve_lifetime::NamedRegionMap,
@@ -443,7 +443,7 @@ impl<'tcx> ctxt<'tcx> {
     /// to the context. The closure enforces that the type context and any interned
     /// value (types, substs, etc.) can only be used while `ty::tls` has a valid
     /// reference to the context, to allow formatting values that need it.
-    pub fn create_and_enter<F, R>(s: Session,
+    pub fn create_and_enter<F, R>(s: &'tcx Session,
                                  arenas: &'tcx CtxtArenas<'tcx>,
                                  def_map: DefMap,
                                  named_region_map: resolve_lifetime::NamedRegionMap,
@@ -452,7 +452,7 @@ impl<'tcx> ctxt<'tcx> {
                                  region_maps: RegionMaps,
                                  lang_items: middle::lang_items::LanguageItems,
                                  stability: stability::Index<'tcx>,
-                                 f: F) -> (Session, R)
+                                 f: F) -> R
                                  where F: FnOnce(&ctxt<'tcx>) -> R
     {
         let interner = RefCell::new(FnvHashMap());
@@ -556,7 +556,6 @@ impl<'a, 'tcx> Lift<'tcx> for &'a Substs<'a> {
 
 pub mod tls {
     use middle::ty;
-    use session::Session;
 
     use std::fmt;
     use syntax::codemap;
@@ -574,17 +573,15 @@ pub mod tls {
         })
     }
 
-    pub fn enter<'tcx, F: FnOnce(&ty::ctxt<'tcx>) -> R, R>(tcx: ty::ctxt<'tcx>, f: F)
-                                                           -> (Session, R) {
-        let result = codemap::SPAN_DEBUG.with(|span_dbg| {
+    pub fn enter<'tcx, F: FnOnce(&ty::ctxt<'tcx>) -> R, R>(tcx: ty::ctxt<'tcx>, f: F) -> R {
+        codemap::SPAN_DEBUG.with(|span_dbg| {
             let original_span_debug = span_dbg.get();
             span_dbg.set(span_debug);
             let tls_ptr = &tcx as *const _ as *const ThreadLocalTyCx;
             let result = TLS_TCX.set(unsafe { &*tls_ptr }, || f(&tcx));
             span_dbg.set(original_span_debug);
             result
-        });
-        (tcx.sess, result)
+        })
     }
 
     pub fn with<F: FnOnce(&ty::ctxt) -> R, R>(f: F) -> R {

src/librustc/session/mod.rs

@@ -15,7 +15,7 @@ use middle::dependency_format;
 use session::search_paths::PathKind;
 use util::nodemap::{NodeMap, FnvHashMap};
 
-use syntax::ast::NodeId;
+use syntax::ast::{NodeId, NodeIdAssigner};
 use syntax::codemap::Span;
 use syntax::diagnostic::{self, Emitter};
 use syntax::diagnostics;
@@ -236,9 +236,6 @@ impl Session {
         }
         lints.insert(id, vec!((lint_id, sp, msg)));
     }
-    pub fn next_node_id(&self) -> ast::NodeId {
-        self.reserve_node_ids(1)
-    }
     pub fn reserve_node_ids(&self, count: ast::NodeId) -> ast::NodeId {
         let id = self.next_node_id.get();
 
@@ -317,6 +314,16 @@ impl Session {
     }
 }
 
+impl NodeIdAssigner for Session {
+    fn next_node_id(&self) -> NodeId {
+        self.reserve_node_ids(1)
+    }
+
+    fn peek_node_id(&self) -> NodeId {
+        self.next_node_id.get().checked_add(1).unwrap()
+    }
+}
+
 fn split_msg_into_multilines(msg: &str) -> Option<String> {
     // Conditions for enabling multi-line errors:
     if !msg.contains("mismatched types") &&